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Asymmetric first-order transition and interlocked particle state in magnetocaloric La(Fe,Si)13

Waske, Anja and Giebeler, Lars and Weise, Bruno and Funk, Alexander and Hinterstein, Manuel and Herklotz, Markus and Skokov, Konstantin and Fähler, Sebastian and Gutfleisch, Oliver and Eckert, Jürgen (2015):
Asymmetric first-order transition and interlocked particle state in magnetocaloric La(Fe,Si)13.
In: physica status solidi (RRL) - Rapid Research Letters, WILEY-VCH Verlag GmbH & Co. KGaA, ISSN 18626254,
[Online-Edition: http://dx.doi.org/10.1002/pssr.201409484],
[Article]

Abstract

In-situ synchrotron XRD measurements of the magnetocaloric material LaFe11.8Si1.2 are used to understand virgin effects and asymmetry of the underlying first order magnetovolume transition. A remarkable change of the transition kinetics occurs after the first cycle, which we attribute to the formation of cracks originating from the volume change. Tomographic imaging revealed that the bulk material disintegrates via an interlocked state where fragments are loosely connected. Though cracks have opened between the fragments, the transition is sharp, which we attribute to magnetostatic interactions. In the cycled sample we find a strong asymmetry between the transition interval upon heating and cooling, which we explain by isostatic pressure acting on parts of the sample during the cooling transition.

Item Type: Article
Erschienen: 2015
Creators: Waske, Anja and Giebeler, Lars and Weise, Bruno and Funk, Alexander and Hinterstein, Manuel and Herklotz, Markus and Skokov, Konstantin and Fähler, Sebastian and Gutfleisch, Oliver and Eckert, Jürgen
Title: Asymmetric first-order transition and interlocked particle state in magnetocaloric La(Fe,Si)13
Language: English
Abstract:

In-situ synchrotron XRD measurements of the magnetocaloric material LaFe11.8Si1.2 are used to understand virgin effects and asymmetry of the underlying first order magnetovolume transition. A remarkable change of the transition kinetics occurs after the first cycle, which we attribute to the formation of cracks originating from the volume change. Tomographic imaging revealed that the bulk material disintegrates via an interlocked state where fragments are loosely connected. Though cracks have opened between the fragments, the transition is sharp, which we attribute to magnetostatic interactions. In the cycled sample we find a strong asymmetry between the transition interval upon heating and cooling, which we explain by isostatic pressure acting on parts of the sample during the cooling transition.

Journal or Publication Title: physica status solidi (RRL) - Rapid Research Letters
Publisher: WILEY-VCH Verlag GmbH & Co. KGaA
Uncontrolled Keywords: magnetic refrigeration, magnetocaloric materials, phase transitions, La(Fe,Si)13, X-ray diffraction
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Functional Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 10 Feb 2015 09:49
Official URL: http://dx.doi.org/10.1002/pssr.201409484
Identification Number: doi:10.1002/pssr.201409484
Funders: A. Waske, B. Weise, S. Fähler and O. Gutfleisch gratefully acknowledge funding by DFG (SPP 1599, www.Ferroic-Cooling.de, WA 3294/1-1, FA 453/11-1, GU 514/3-1)., K. P. Skokov is grateful to the European Community’s 7th Framework Program under the grant agreement No. 310748 (DRREAM).
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